Stop-motion switch for sewing machine bobbin thread



E. VOSSEN May 22, 1956 STOP-MOTION SWITCH FOR SEWING MACHINE BOBBINTHREAD Filed June 1, 1953 If, g a

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INVENTOR QM/P0 1/0555 QLMQ ATTORNEY United States Patent STOP-MOTIONSWITCH FOR SEWING MACHINE BOBBIN THREAD Edward Vossen, Lynbrook, N. Y.,assignor to Stepdviotien Devices Corp., Brooklyn, N. Y.

Application June 1, 1953, Serial No. 358,823

Claims. (Cl. 200---61.18)

This invention relates to a stop-motion switch for sewing machine bobbinthread.

Thread is fed to the needles of conventional sewing machines, used bothin the home and in industry, from a spool or spools which are generallysituated on or above the sewing machine, in plain view, and from abobbin or a plurality of bobbins situated in or below the base of themachine, generally hidden from view. When the needle thread happens tobreak or terminate, that fact becomes almost immediately apparent to theoperator of the machine but when a break occurs in the bobbin thread, orwhen the bobbin thread terminates, such event frequently escapes theattention of the operator until the machine has run a considerable timewithout the benefit of the bobbin thread.

This invention pertains solely and exclusively to the bobbin thread andthe principal object of this invention is the provision of a stop-motionswitch which is virtually instantaneously engaged and actuated by theneedle thread immediately upon the severance or termination of thebobbin thread. It will be understood that this engagement of the switchby the needle thread takes place immediately above the presser foot ofthe machine, be-

ween its shank and the needle. In the normal operation of the machine,when all of the thread is continuous and unbroken, the needle threadwill assume a substantially vertical position on the upward movement ofthe needle, between said needle and the presser foot. When the bobbinthread is severed or terminated, however, the needle thread will assumean angular position between the needle and the crook of the presser footwhen the needle moves upwardly to its retracted position.

The foregoing is predicated upon the use of a presser foot made ormodified as shown in the drawing and described in the specification. Aconventional presser foot constructed without regard or relation to astop-motion mechanism of the character described is provided with only arelatively small hole for the needle and needle thread. The small sizeof the needle hole in the presser foot prevents the needle thread fromassuming an inclined position when the bobbin thread breaks orterminates. In the present invention, the needle hole in the presserfoot is elongated in rearward direction and a rearwardly and downwardlysloping channel is formed in the bottom of the presser foot behind andin communication with said elongated needle hole. Consequently, when theneedle thread is disengaged by the bobbin thread, it is enabled toassume an angular position behind the needle and through said elongatedneedle hole and sloping channel. It is this angularly positioned threadwhich engages the stop-motion switch herein described and claimed.

The stop-motion switch which comprises the present invention consists oftwo mechanisms which are associated with each other. The first is atrigger mechanism which is actuated by the angularly positioned needlethread. The second is a switch mechanism which is actuated by thetrigger mechanism. In turn, the switch mechanism actuates thestop-motion mechanism which is adapted to disengage the sewing machineclutch. More precisely, when the bobbin thread breaks or terminates, theneedle thread assumes its angular position and thereby engages andactuates the trigger mechanism. The trigger mechanism is set ofi orreleased and it engages and closes the switch mechanism. The circuit tothe stop-motion mechanism is thereby closed and said stop-motionmechanism then operates to disengage the sewing machine clutch and tostop the operation of the sewing machine. The stopmotion mechanism maybe conventional and it will neither be shown nor described herein.

Stop-motion switches which stop a sewing machine upon the breaking ortermination of the bobbin thread are known to the prior art. It isimportant, however, that they operate as quickly as possible to preventlengthy operation of the machine following the breaking of the bobbinthread or its termination. In the present invention, the stop-motionswitch action is so fast that the machine is caused to stop beforeaflected area of the work passes the presser foot. No stop-motion switchmechanism known to the prior art is capable of functioning as quickly asthe stop-motion switch mechanism herein described and claimed.

An important feature of this invention is the re-setting or cockingmeans which is associated with the trigger mechanism. This re-settingmeans consists simply of a small knob or similar handle which isprovided with an arm that engages the trigger mechanism. When the knobis turned but a few degrees in one direction, it sets or cooks thetrigger mechanism. When the bobbin thread breaks or terminates and theneedle thread assumes its angular position to engage and release thetrigger mechanism, the knob is automatically returned to its originalposition whence it may again be turned in the opposite direction toreset the trigger mechanism.

A preferred form of this invention is shown in the accompanying drawingin which:

Fig. 1 is a side view of a stop-motion switch for sewing machine bobbinthread, showing said switch mounted on the base plate of a sewingmachine.

Fig. 2 is a top view thereof.

Fig. 3 is a front view.

Presser foot 10 shown in the drawing is a conventional sewing machinepresser foot with the exception that it is provided with an elongatedopening 12 for needle 14 and an inclined channel 16 at the rear of saidneedle opening and communicating therewith. Channel 16 slopes backwardlyand downwardly from the needle opening in order to provide a relativelywide range of movement for the needle thread 18 in rearward direction atsuch time as it is disengaged from the bobbin thread when the latter iseither broken or terminated. This elongated opening and the slopingchannel which communicates with it are exaggerated in the drawing forpurposes of clarity and it will be seen that they make it possible forthe needle thread to assume its angular position indicated by the solidlines in Fig. 1 immediately upon the breaking or termination of thebobbin thread. interrupted lines 18a indicate the normal position of theneedle thread when the bobbin thread is properly engaged thereby.

Also conventional is shank 25) which supports the presser foot on sewingmachine base 22. The work 24 moves between the presser foot and plate 26which is supported by said base. Mounted on the head 27 of the machineis housing 23 of stop-motion switch 33. The housing or casing may beentirely enclosed to protect the working parts of the switch but, againfor purposes of clarity, it is shown in the drawing as an open casing.In one form of this invention, the casing has a top wall 32, a back wall34, a front wall 36, a bottom wall 38, and a pair of side walls 40 and42 respectively. The front wall 36 is provided with an upwardlyextending bar d4 which has a pair of aligned elongated holes 46 and 48formed therein. Screws '50 projecting through said elongated holessecure bar 44 to the head 27 of the sewing machine and it is by thismeans that the entire stopmotion switch mechanism is mounted thereon.

The trigger mechanism of switch mechanism 30 is interposed,functionally, between the probe or feeler S2 and the switch proper. Theprobe is simply a wire or the like which has a laterally extendingfeeler portion 52.4, a longitudinally extending shank portion 52b, and avertically extending back end portion 520' which is secured to a shaft54. Shaft 54 projects through and is rotatably supported by side Wall 40of the casing. It also projects through and is supported by side wall 42of the casing and it is thereby provided with two bearing supports.

This shaft 54 carries an arm 56 securely fixed thereto. Spacers may beprovided on said shaft between said arm 56 and the two side walls of thecasing. Since arm 56 is fixed to "shaft 54 and since probe 52 is alsofixed to said shaft, all three elements will move integrally with eachother. Shaft 54 is free to turn about its own axis in its two side wallsupports. When the bobbin thread breaks or terminates, the needle thread18 will assume its angular position shown in Fig. l and it will engageprobe 52 and cause said probe to pivot with shaft 54 and arm 56 aboutthe axis of said shaft. It is this pivotal movementthat releases thetrigger mechanism and actuates the switch.

A tension spring 58 is secured at one end to the inside of side wall 40and at its opposite end to one end of arm 56. As viewed in Fig. 1,spring 58 acts to pivot arm 56 in clockwise direction. The opposite endof arm 56 is engageable with a shoulder 60 formed on slide '62. Slide 62has a horizontally'extending portion 62a, a downwardly extending endportion 62b and a second horizontally extending portion "62c. Horizontalportion 62a is situated above and in parallel relation to horizontalportion 620. Horizontal portion 62a is the shorter of the two horizontalportions and on it is formed shoulder 60 above mentioned. The lowerportion 62c is the longer of the two horizontal portions and it isslidably supported by yoke 64. This yoke is slotted at both ends toaccommodate horizontal portion 620 and to enable said horizontal portionto slide horizontally of itself either forwardly or backwardly asthecase'may be. 'It will be seen that yoke 64 is provided with adownwardly extending side plate 66 which is secured by means of screws68 to side wall 40 of the casing. Projecting downwardly from horizontalportion 62c, through an elongated-opening 70 in yoke 64, is a pin 72.Secured at one end to said pin .is a tension spring 74 and said tensionspring is secured at its opposite end to side wall 40 of the casing. Theaction of spring 74 is to retract slide 62, that is, to pull itbackwardly or leftwardly as viewed in Fig. 1.

An opening 76 is formed in the upper portion 62:: of slide 62.Projecting through said opening is an arm 78 secured to a shaft '30which projects through and is rotatably supported by side walls 40 and42 of the casing. A knob 82 is secured to one outwardly projecting endof shaft 80. Knob 82 may be turned manually to the extent of only a fewdegrees in order to move slide 62 forwardly (rightwardly as viewed inFig. 1) until shoulder 60 clears arm 56. Tension spring 58 will therebybe enabled to pivot arm 56 in clockwise direction as viewed in Fig. 1until it engages shoulder 60. Knob 82 may now be released and slide 62will be prevented from moving backwardly (leftwar'dly as viewed inFig. 1) in response to the action of spring 74 thereon, since itsshoulder 60 now abuts arm 56. The trigger mechanism, which cornpris'esarm 56 and spring 58 acting thereon and slide 62 and spring 74 actingthereon, is now cocked and ready for action.

When the bobbin thread breaks or comes to an end, needle thread 18 willassume its inclined Fig. 1 position and it will engage probe 52 andcause it to pivot slightly in counter-clockwise direction as viewed inFig. 1. Since the probe is fixed to shaft 54 to which arm 56 is likewisea'tfixed, such pivotal movement of the probe will be reflected in acorresponding pivotal movement of arm 56. This will cause arm 56 todisengage shoulder 60 and slide 62 will thereupon be caused to slideleftwardly as viewed in Fig. 1 in response to the action of spring 74thereon.

When slide 62 moves backwardly in response to the action of spring 74(leftwardly as viewed in Fig. 1) its horizontal portion 620 will becaused to thrust switch arm in the direction of and into engagement withswitch arm 92. Switch arm 90 is a leaf spring which is bowed to form ahorizontal portion 901: and a vertical portion 90!) joined by a bight900. The horizontal portion 90a is secured by means of bolt 94 to thetop wall 32 of the casing. An insulating ,pad'96 prevents electricalcontact between said horizontal portion 90a and the top wall of thecasing. Bolt 94 also serves as a binding post or terminal and it issimilarly insulated from the casing. An insulating pad 98 is secured tothe vertical portion 9% of said contact member 90, on the side facingslide 62. Consequently,when slide 62 acts'upon contact 90 to thrust itleftwardly, there is no electrical engagement between said slide andsaid contact by reason of the presence of insulating pad 98.

Contact '92 may also be a leaf spring secured to wall 34 of the casingbymeans of bolt 1%. An insulating pad 162 is disposed between contactmember 92 and said wall 34 of the casing to prevent electricalengagement thereb'etween. Bolt 1% "is also insulated from the casing andit may also serve as abinding post or terminal. Contact member '92 maybebent upwardly at its lower end to provide a resilient contact portion92a. When slide 62 pushes against insulating pad 98, contact member 90flexes and is thrust into engagement with contact portion 92a of Contact92 and the circuit to the stop-motion mechanism (not shown) is therebyclosed and the stopmotion mechanism goes into operation to stop themachine. Contact 99 is normally biased away from contact 92.

The foregoing is illustrative of a preferred form of this invention andit will clearly be understood that this preferred form may be modifiedand other forms may be provided within the broad spirit and scope of theinvention and the appended claims.

I claim:

1. A stop-motion switch for a sewing machine, comprising a casing,fastening means adapted to secure the casing to a sewing machineadjacent its presser foot, a probe pivotally mountedon said casing andadapted to project between said presser foot and the needle of saidmachine, a trigger mechanism in said casing connected to and actuated bysaid probe, and a switch mechanism in said casing which is connected toand actuated by said trigger mechanism, wherein the trigger mechanismcorn prises apivotally movable arm and a longitudinally movable slide,both mounted in said casing, and each being engageable with the other, aspring connected to the pivotally mounted arm and tending to maintainsaid arm in engagement with the slide, and a second spring in engagementwith the slide to thrust said slide in a predetermined directionrelative to said arm when said arm is caused to disengage said slideagainst the action or the first mentioned spring.

. 2. A stop-motion switch for a sewing machine, comprising a casing,fastening means adapted to secure the casing to a sewing machineadjacent its presser foot, a probe pivotally mounted on said casing andadapted to project between said presser foot andthe needle of saidmachine, a -trigger mechanism in said casing connected to and actuatedby said probe, and a switch mechanism in said casing which is connectedto and actuated by said trigger mechanism, wherein the probe is fixed toa shaft which is-rotatably supported by the casing to enable said probeto pivot in either direction about the longitudinal axis of said shaft,and the trigger mechanism is connected to said shaft, said triggermechanism comprising an arm which is fixed to said shaft and which isintegrally movable with said shaft and with said probe, a movablymounted slide adjacent said arm, said arm being pivotally movable withsaid shaft and said probe into and out of engagement with said slide, atension spring connected to said arm and urging it into engagement withsaid slide, and a second spring connected to said slide and urging it tomove in a given direction against the action of said arm when said armis in engagement with said slide.

.3. A stop-notion switch for a sewing machine, comprising a casing,fastening means adapted to secure the casing to a sewing machineadjacent its presser foot, a probe pivotally mounted on said casing andadapted to project between said presser foot and the needle of saidmachine, a trigger mechanism in said casing connected to and actuated bysaid probe, and a switch mechanism in said casing which is connected toand actuated by said trigger mechanism, wherein the switch mechanism comprises a fixed contact member and a movable contact member, both mountedwithin the casing, said movable contact member being movable into andout of engagement with the fixed contact member and being biased formovement out of engagement with said fixed contact member, a slide, saidslide being mounted for engagement with the movable contact member, andfor movement toward and away from the fixed contact member and urgingsaid movable contact member to move in the direction of the fixedcontact member to bring the movable contact member into engagement withthe fixed contact member, means for manually retracting the slideagainst the action of said spring to release the movable contact memberfor biased movement out of engagement with the fixed contact member, arotatably mounted shaft, an arm fixed to said shaft for pivotal movementinto engagement with the slide to prevent movement of said slide in thedirection of the fixed contact member and thereby to prevent engagementof the movable contact member with the fixed contact member, and secondspring connected to said arm and acting to maintain it in engagementwith said slide, said probe being also fixed to said shaft and beingmovable integrally therewith and with said arm, whereby actuation of theprobe causes the arm to disengage the slide and the slide to move themovable contact member into engagement with the fixed contact member.

4. A stop-motion switch for a sewing machine, comprising a casing,fastening means adapted to secure the casing to a sewing machineadjacent its presser foot, a probe pivotally mounted on said casing andadapted to project between said presser foot and the needle of saidmachine, a trigger mechanism in said casing connected to and actuated bysaid probe, and a switch mechanism in said casing which is connected toand actuated by said trigger mechanism, wherein the trigger mechanismcomprises a pivotally movable arm and a longitudinally movable slide,both mounted in said casing, each being movable in one direction to aposition where it is out of engagement with the other and each beingmovable in the opposite direction to a position where it is engageablewith the other, a spring connected to the pivotally movable arm andurging it in said opposite direction for engagement with the slide, asecond spring connected to the slide and urging it in the firstdirection out of engagement with the pivotaliy movable arm, and manuallyactuated means connected to said slide for moving it in said oppositedirection into engagement with the pivotally movable arm against theaction of said second spring, both springs acting to maintain the armand the slide in engagement with each other after the manually actuatedmeans and the first mentioned spring have brought said arm and saidslide into engagement with each other.

5. A stop-motion switch for a sewing machine, comprising a casing,fastening means adapted to secure the casing to a sewing machineadjacent its presser foot, a probe pivotally mounted on said casing andadapted to project between said presser foot and the needle of saidmachine, a trigger mechanism in said casing connected to and actuated bysaid probe, and a switch mechanism in said casing which is connected toand actuated by said trigger mechanism, wherein the trigger mechanismcomprises a pivotally movable arm and a longitudinally movable slide,both mounted in said casing, each being movable in one direction to aposition where it is out of engagement with the other each being movablein the opposite direction to a position where it is engageable with theother, a spring connected to the pivotally movable arm and urging it insaid opposite direction for engagement with the slide, a second springconnected to the slide and urging it in the first direction out ofengagement with the pivotally movable arm, and manually actuated meansconnected to said slide for moving it in said opposite direction intoengagement with the pivotally movable arm against the action of saidsecond spring, both springs acting to maintain the arm and the slide inengagement with each other after the manually actuated means and thefirst mentioned spring have brought said arm and said slide intoengagement with each other, said switch mechanism comprising a fixedcontact member and a movable contact member, both mounted within thecasing, said movable contact member being movable into and out ofengagement with the fixed contact memher and being biased for movementout of engagement with said fixed contact member, said movable contactmember being situated adjacent said slide and being biased against theslide in opposition to the action of the second mentioned spring,whereby the slide thrusts the movable contact member into engagementwith the fixed contact member when the slide is disengaged from thepivotally movable arm and is thrust in said first mentioned direction bythe action of said second spring.

References Cited in the file of this patent UNITED STATES PATENTS1,455,387 Cobb May 15, 1923 2,387,369 Vossen Oct. 23, 1945 2,387,958Vossen Oct. 30, 1945 2,410,718 Crawford Nov. 5, 1946 2,643,305 ManssonJune 23, 1953

